The present invention relates to a furnace for melting a charge and, more particularly, to such a furnace comprising a space overlying a charge into which opens at least one oxygenated gas injector passing through the circumference of the furnace to deliver into this space a gas jet which is nonradial relative to the central vertical axis of the furnace. The present invention also relates to a gas injector designed for such a furnace.
There is known from U.S. Pat. No. 5,166,950, in the name of the applicant and hereinafter called "the mentioned patent", a process and installation for melting a charge in a furnace, particularly an electric furnace for the melting of scrap for the production of steel, by bringing fusion energy to the charge and with post-combustion of the fumes by injection of an oxygenated gas into a space in the furnace located above the charge.
In FIGS. 1 and 2 of the mentioned patent, there is shown a furnace with a substantially circular side wall traversed obliquely by two sets of straight oxygenated gas injectors, these injectors being oriented in substantially horizontal directions nonradially relative to the vertical axis of the furnace, so as to create rotating gas currents turning in opposite directions in the space within the furnace located above the charge. There is thus ensured an efficacious mixture of the oxygenated gas with combustible gases (CO, H.sub.2) emitted by the charge so as to give rise to a homogenous post-combustion of these gases in the furnace, which contributes to melting of this charge, in cooperation with vertical electrodes distributed about and in the vicinity of the vertical axis of the furnace.
It is obviously necessary to provide, in the side wall of the furnace, passages for the injectors. With straight injectors passing obliquely through this wall, as shown in the mentioned document, it will be understood that the passages to be provided must be relatively wide, so that they will permit necessary adjustments of the position of the axis of the injector in all directions in the space, this position being adapted to vary from one type of furnace to another. The presence of wide passages in the side wall of the furnace obviously constitutes a drawback, worsened when the number of injectors is increased to improve the agitation of the gases used in post-combustion.
The injectors of the furnace of the mentioned patent protrude substantially within the periphery of the furnace. If this latter is supplied vertically by the scrap iron to be melted, pieces of scrap iron can thus damage the ends of the injectors by striking these when they fall. These protuberant ends are also threatened by blockages due to the projection of slag or metal from the melting mass.